   [rdd storage-level]
   (.persist rdd storage-level))
 
+(defn unpersist
+  [rdd]
+  (.unpersist rdd))
+
 (def first
   "Returns the first element of `rdd`."
   (memfn first))

  ([rdd]
   (.name rdd)))

(defn union
  "Build the union of two or more RDDs"
  [context rdd & rdds]
  (.union context rdd (ArrayList. rdds)))

(defn partitionwise-sampled-rdd [rdd sampler preserve-partitioning? seed]
  "Creates a PartitionwiseSampledRRD from existing RDD and a sampler object"
  (-> (PartitionwiseSampledRDD.

  [rdd f]
  (.filter rdd (function (ftruthy? f))))

(defn union
  "Union `rdd` and `other`. duplicate keys are kept."
  [context rdd & rdds]
  (.union rdd other))

(defn foreach
  "Applies the function `f` to all elements of `rdd`."
  [rdd f]
